For the numerical evaluation, the SER is considered. We assume that the channel gains are modeled by independent Rayleigh fading [1]}, meaning \(\beta _m=1 \ \text{for} \ m=1,...,M\)  and \(g_{k,m}\sim \mathcal {CN} ({0},\sigma _g^2)\ \text{for} \ k=1,...,K \ \text{and}\ m=1, ...,M\)  as done implicitly in [2]} and [3]} and explicitly in [4]}. Moreover, the SNR is defined by \(\mathrm {SNR}=\frac{ \left\Vert x\right\Vert ^2_2 }{N_0}\) , where the spectral noise power density \(N_0\)  is equivalent to the noise sample variance \(\sigma _w^2\) . For the MSEP B&B methods \(\delta \)  is set to \(\delta =5 \cdot 10^{-7}\) .
